Optical Feedback Regimes Suitable for Distance Measurement with a Ring Laser

We numerically study the behavior of a ring laser subject to bidirectional delayed optical feedback, when the isolated laser is in the quasi-unidirectional regime. We find different regimes, two of which are of special interest, because the laser switching period, between the clockwise and the counter-clockwise mode, is linearly related to the time of flight from the laser to one or both remote reflectors. These regimes are thus suitable to implement a telemeter.